The present invention relates generally to a method and apparatus for connectorizing, testing and inspecting fiber optic cables and, more specifically, a method and apparatus for automatically connectorizing, testing and inspecting fiber optic cables.
Fiber optic networks are employed in an increasing and varied number of applications for transmitting voice, data and other information. For example, fiber optic networks are utilized in a wide variety of aerospace applications for transmitting data at high speeds and with relatively low loss. Each of these fiber optic networks includes a number of optical fiber links. In turn, each optical fiber link generally includes a fiber optic connector mounted to the opposed ends thereof. This connectorization process is further complicated since each end face of the optical fiber must generally be precisely polished and cleaned after mounting the ferrule, but before mounting the remainder of the connector thereon. Thus, there is a risk of losing this expensive ferrule, if the polishing process is not successful. The industry""s failure rate of polishing is approximately 10% and the cost of each ferrule, such as ITT Cannon part number NFOC-F15PB, is $150. In addition, the connectorized optical fiber must oftentimes be inspected to insure compliance with performance specifications thereby further increase on labor costs. As a result, it typically takes approximately 20 minutes to manually connectorize one end of a fiber optic cable.
Current techniques for mounting connectors upon the end portions of fiber optic cables are generally quite complicated and labor intensive and may oftentimes require specially trained technicians and inspectors. As a result, the connectorization costs may quickly become unnecessarily large, particularly in view of the large number of fiber optic cables that must typically be connectorized by an aircraft manufacturer. In addition, current connectorization techniques often have poor repeatability, thereby producing fiber optic cables which have a wide variety of operating characteristics.
A number of automated techniques have therefore been developed for automatically mounting connectors upon the end portions of a fiber optic cable. For example, U.S. Pat. No. 5,394,606 to Isamu Knoshita, et al. and U.S. Pat. No. 4,944,079 to Kunio Nakamura, et al. describe automated devices for connectorizing a fiber optic cable. Unfortunately, each of these automated techniques is limited to mounting one particular type of connector upon the end portion of a common fiber optic cable and is not designed to mount the wide variety of connectors upon the end portions of respective different fiber optic cables that are demanded by many modern applications, such as aerospace and local area network (LAN) applications.
It is therefore an object of the present invention to provide an improved method and apparatus for automatically connectorizing fiber optic cables.
It is another object of the present invention to provide a method and apparatus for automatically mounting any one of a variety of connectors upon the end portion of a fiber optic cable.
It is a further object of the present invention to provide an improved method and apparatus for automatically inspecting and classifying optical fibers during the connectorization process.
It is yet another object of the present invention to provide an improved method and apparatus for automatically testing the optical performance of a fiber optic cable after the connectorization process.
These and other objects are provided, according to one embodiment of the present invention, by a method and apparatus for mounting any one of a plurality of types of connectors upon the end portion of a fiber optic cable. According to this embodiment, the automated fiber optic connectorization apparatus includes a memory device for storing data relating to a plurality of types of connectors, such as the parts and supplies required to assemble each type of connector, and data relating to the fiber end-face geometry and corresponding optical performance data. The automated fiber optic connectorization apparatus also includes a controller for receiving input data that describe the detailed requirements for each fiber optic link, such as from a system operator, a wire data list, or other source, that specifies the type of connector to be mounted upon the end portion of the optical fiber. Based upon this input, the controller determines the components, i.e., the parts and supplies, required to mount the specified type of connector upon the end portion of the fiber optic cable based upon the data stored by the memory device. The automated fiber optic connectorization apparatus also includes means for obtaining the necessary components and means for assembling these components upon the end portion of the fiber optic cable. As a result, the automated fiber optic connectorization apparatus of this embodiment of the present invention can automatically mount the specified type of connector of the type upon the end portion of the fiber optic cable.
In addition to inputting the type of connector, the system operator, wire data list, or other source can also specify the length of the resulting fiber optic cable. Accordingly, the automated fiber optic connectorization apparatus of one embodiment includes a cutter for automatically cutting and stripping the cable components to varying lengths. Notably, the automated fiber optic connectorization apparatus can also include means for automatically polishing the end face of the optical fiber and inspecting the end face prior to mounting the connector upon the end portion of the optical fiber. Thus, the task of mounting the connector proceeds only if the polished surface of the fiber end-face has been inspected and is found to be acceptable.
To handle this task, a cassette is also provided for preparing the end face of an optical fiber, such as for polishing or cleaning the end face of an optical fiber. The cassette includes a housing defining a window and a supply reel and a take up reel disposed within the housing. The cassette contains preparatory tapes, such as a polishing strip and a cleaning strip, that advances from the supply reel to the take up reel for preparing the end face of the optical fiber. Further, the cassette includes means for directing the tape by the window defined by the housing such that the tape contacts and prepares the end face of the optical fiber, such as by polishing or cleaning the end face of the optical fiber. For example, the directing means can include a resilient pad aligned with the window defined by the housing and disposed interior of the preparatory tape within the housing for supporting the preparatory tape during contact with the end face of the optical fiber. In order to properly prepare the end face of the optical fiber, the cassette also preferably includes means for controllably moving the housing relative to the end face of the optical fiber.
The automated fiber optic connectorization apparatus can also include means for automatically inspecting the optical fiber after the end face of the optical fiber has been polished. According to this embodiment, an automated optical fiber inspection apparatus is provided for automatically inspecting and classifying the polished end face of an optical fiber before proceeding to the next step, i.e. prior to connectorizing the fiber optic cable. According to this embodiment, the automated optical fiber inspection apparatus includes a memory device for storing predefined data sets relating to at least one characteristic of the end face of the optical fiber. For example, the data sets can be representative of images of acceptable end faces and unacceptable end faces.
The automated optical fiber inspection apparatus of this embodiment can also include an imaging system for obtaining an image, preferably a composite image generated from a series of captured images, characterizing the end-face contour of the optical fiber and means for comparing this composite image of the end face of the optical fiber against the predefined data sets relating to at least one characteristic of the end face of the optical fiber so as to automatically determine the xe2x80x9cbest-matchxe2x80x9d data set. Since each predefined data set has been classified as acceptable or unacceptable, the automated optical fiber inspection apparatus determines the acceptability of the end-face contour based upon the classification of the best-match data set. According to one advantageous embodiment, the automated optical fiber inspection apparatus can also include means for automatically determining if an unacceptable optical fiber can be corrected, such as by repolishing, or if the unacceptable optical fiber must be completed reworked, beginning by recleaving the end portion of the optical fiber. The automated optical fiber inspection apparatus can also include means, such as a test station, for testing the connectorized fiber optic cable to guarantee predefined optical operating parameters, such as optical loss or optical back-reflection.
During the process for automatically inspecting and connectorizing a fiber optic cable, the fiber optic cable is preferably carried by an optical fiber cartridge assembly which presents the appropriate segment of the fiber optic cable for jacket stripping, fiber cleaving, and end-face polishing operations. According to this embodiment, the optical fiber cartridge assembly includes an optical fiber cartridge including a platform, a reel rotatably mounted upon the platform, and first and second gripping means mounted upon the platform for holding the first and second opposed ends of the optical fiber, respectively. The optical fiber cartridge of this embodiment also includes means for rotating the platform relative to the reel such that the optical fiber is wound about the reel. In this regard, the optical fiber cartridge can include means for raising the reel relative to the platform during the rotation of the platform relative to the reel.
By providing for the automatic connectorization of fiber optic cables, the automatic fiber optic connectorization method and apparatus of the present invention significantly reduces the time and labor required to mount connectors upon the end portions of fiber optic cables, thereby increasing productivity. As a result, the automated fiber optic connectorization apparatus can be readily operated by technicians with very little training. The efficiency and yield of the automatic connectorization process of the present invention is further advanced by the automated optical fiber inspection apparatus of one embodiment that insures that the optical fibers have been properly polished prior to mounting of the expensive connectors and, if an optical fiber is unacceptable, automatically determines if the optical fiber must be repolished or otherwise reworked. In contrast to conventional automated connectorization techniques, the automated fiber optic connectorization apparatus of the present invention can advantageously mount any one of a plurality of types of connectors upon the end portion of a fiber optic cable based upon input by the system operator or other source, thereby permitting rapid customization of the automated fiber optic connectorization apparatus.